Classifications

• • H—ELECTRICITY
  • H04—ELECTRIC COMMUNICATION TECHNIQUE
  • H04N—PICTORIAL COMMUNICATION, e.g. TELEVISION
  • H04N13/00—Stereoscopic video systems; Multi-view video systems; Details thereof
• • G—PHYSICS
  • G06—COMPUTING; CALCULATING OR COUNTING
  • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
  • G06T15/00—3D [Three Dimensional] image rendering
• • G—PHYSICS
  • G06—COMPUTING; CALCULATING OR COUNTING
  • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
  • G06T17/00—Three dimensional [3D] modelling, e.g. data description of 3D objects
  • G06T17/005—Tree description, e.g. octree, quadtree
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B27/00—Editing; Indexing; Addressing; Timing or synchronising; Monitoring; Measuring tape travel
  • G11B27/10—Indexing; Addressing; Timing or synchronising; Measuring tape travel
  • G11B27/19—Indexing; Addressing; Timing or synchronising; Measuring tape travel by using information detectable on the record carrier
  • G11B27/28—Indexing; Addressing; Timing or synchronising; Measuring tape travel by using information detectable on the record carrier by using information signals recorded by the same method as the main recording
  • G11B27/32—Indexing; Addressing; Timing or synchronising; Measuring tape travel by using information detectable on the record carrier by using information signals recorded by the same method as the main recording on separate auxiliary tracks of the same or an auxiliary record carrier
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B27/00—Editing; Indexing; Addressing; Timing or synchronising; Monitoring; Measuring tape travel
  • G11B27/10—Indexing; Addressing; Timing or synchronising; Measuring tape travel
  • G11B27/19—Indexing; Addressing; Timing or synchronising; Measuring tape travel by using information detectable on the record carrier
  • G11B27/28—Indexing; Addressing; Timing or synchronising; Measuring tape travel by using information detectable on the record carrier by using information signals recorded by the same method as the main recording
  • G11B27/32—Indexing; Addressing; Timing or synchronising; Measuring tape travel by using information detectable on the record carrier by using information signals recorded by the same method as the main recording on separate auxiliary tracks of the same or an auxiliary record carrier
  • G11B27/322—Indexing; Addressing; Timing or synchronising; Measuring tape travel by using information detectable on the record carrier by using information signals recorded by the same method as the main recording on separate auxiliary tracks of the same or an auxiliary record carrier used signal is digitally coded
• • G—PHYSICS
  • G06—COMPUTING; CALCULATING OR COUNTING
  • G06T—IMAGE DATA PROCESSING OR GENERATION, IN GENERAL
  • G06T2210/00—Indexing scheme for image generation or computer graphics
  • G06T2210/61—Scene description
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B2220/00—Record carriers by type
  • G11B2220/20—Disc-shaped record carriers
  • G11B2220/25—Disc-shaped record carriers characterised in that the disc is based on a specific recording technology
  • G11B2220/2537—Optical discs
  • G11B2220/2541—Blu-ray discs; Blue laser DVR discs

Definitions

• the present invention relates to a scene graph suitable for defining stereoscopic graphical objects, to a method and an apparatus for creating such scene graphs, and to a method and an apparatus for rendering graphical objects based on such scene graphs. Furthermore, the invention relates to a storage medium comprising a scene graph for defining a stereoscopic graphical object. Finally, the invention relates to a method for initializing a rendering module and a storage medium comprising an application adapted to perform this method.
• a scene graph In general, such a scene graph describes - usually in a hierarchical manner, e.g. a tree structure - how graphical elements are arranged in space and time to compose scenes.
• a prominent example of a scene graph is the hypertext markup language HTML, as used for web pages in the internet.
• HTML hypertext markup language
• a scene graph can be created with the help of visual design software.
• software capable of interpreting the scene graph renders it on the screen. For example, in case of HTML, rendering is performed by the internet browser.
• scene graph or the user interface can be generated relatively easy with the help of visual design software tools.
• scene graph is usually platform-independent. Only the rendering software depends on the platform.
• the Blu-ray Disc Association has published stereoscopic 3D extensions to their pre-recorded format.
• the format not only allows to store stereoscopic 3D video on the Blu-ray disc, it also supports creation of stereoscopic 3D user interfaces, for example 3D pop-up menus.
• the Blu-ray 3D format is designed to enable backwards compatibility. The goal is that when authored properly, the same Blu-ray disc should be
• the first problem is how to efficiently create such stereoscopic user interfaces.
• the second problem is how to efficiently create the user interfaces for both stereoscopic 3D mode as well as for 2D mode.
• a further option would be to make use of model virtual 3D worlds in form of full-fledged 3-dimensional scene graphs, as known from computer games. Such an approach is also capable of rendering a 2D version as well as a stereoscopic version of the scene.
• the computational cost of such an approach is quite high and usually requires some hardware acceleration support, e.g. 3D graphics acceleration of modern computer graphics adapters. Such processing power is typically not available on consumer electronics devices.
• the scene graph describing a spatial and/or temporal arrangement of the stereoscopic
• graphical object comprises:
• a scene graph for a stereoscopic graphical object the scene graph describing a spatial and/or temporal
• the scene graph comprises information about image data for a base image for the stereoscopic graphical object, image data for a dependent image for the graphical object, and the spatial and/or temporal arrangement of the base image and the dependent image .
• a storage medium comprises a scene graph for a stereoscopic graphical object, the scene graph describing a spatial and/or temporal arrangement of the stereoscopic
• the scene graph comprises information about image data for a base image for the stereoscopic
• the graphical object is composed of the base image and the
• the graphical object is composed of the base image only .
• a first aspect of the invention is the definition of a
• stereoscopic' scene graph i.e. a scene graph that is
• stereoscopic graphical objects e.g. stereoscopic user interfaces.
• Such stereoscopic graphical objects may be provided, for example, on Blu-ray 3D discs.
• the proposed scene graph is particularly suited for automatically deriving a 2D-representation from a stereoscopic graphical object by using only the specified base image. This makes the scene graph useful for heterogeneous 3D/2D playback systems.
• 3D/2D compatible content e.g. a 3D Blu-ray disc
• the content author is freed from creating one graphical object for stereoscopic 3D mode and another graphical object for monoscopic 2D mode.
• an authoring system will provide a graphical user interface for defining or generating the base image and the dependent image .
• the image data for the base image is contained in a base image mosaic and/or the image data for the dependent image is contained in a dependent image mosaic.
• Image mosaics allow to reduce loading times and improve the player
• image mosaics contain only image data for base images and only image data for dependent images it is guaranteed that no resources are loaded that, to at least some extent, contain images that are not needed for the current rendering mode.
• the image mosaics will generally be generated by a dedicated software, which optimizes the distribution of the selected images into different image mosaics.
• a method for rendering a stereoscopic graphical object comprises the steps of :
• a scene graph which comprises information about image data for a base image and image data for a dependent image for the stereoscopic graphical object as well as a spatial and/or temporal arrangement of the base image and the dependent image;
• an apparatus for rendering a stereoscopic graphical object comprises:
• image data for a base image and image data for a dependent image for the stereoscopic graphical object as well as a spatial and/or temporal arrangement of the base image and the dependent image
• the second aspect of the invention is related to a rendering method and apparatus, which make use of the scene graph, the base image, and the dependent image.
• An important advantage of the proposed scene graph is that it is capable of being efficiently rendered either in stereo 3D mode or in monoscopic 2D mode. This makes the scene graph very useful for systems like Blu-ray 3D discs, where for example a stereo 3D user interface needs to be generated in stereo 3D mode when executing on a 3D player, and a monoscopic user interface when running on a system which is 2D-capable only.
• a stereo 3D user interface needs to be generated in stereo 3D mode when executing on a 3D player
• a monoscopic user interface when running on a system which is 2D-capable only.
• a 2D rendering mode only the image data for the base images need to be retrieved and rendered, whereas in case of a 3D rendering mode the image data for the base images as well as the image data for the dependent images are
• a transducer will retrieve the necessary images from a storage medium, e.g. an optical pickup in case of optical storage media or a reading head in case of a hard disk.
• the image data for the dependent image are also retrieved in case of rendering a monoscopic version of the stereoscopic graphical object.
• the image data for the dependent image are also retrieved in case of rendering a monoscopic version of the stereoscopic graphical object.
• a 3D rendering mode is possible, i.e. if a 3D rendering mode is supported by a rendering device;
• the image data for the base image and the image data for the dependent image specified by the scene graph are retrieved irrespective of an actual rendering mode.
• a 3D rendering mode it is checked whether a 3D rendering mode would actually be possible.
• a 3D player connected to a 3D display may be set to a 2D rendering mode, though a 3D rendering mode would be
• the image data for the dependent images are favorably loaded even though they are no needed for the current rendering mode.
• the user decides to switch to 3D rendering mode, all necessary images are already available. Hence, switching from a 2D rendering mode to a 3D rendering mode is accomplished very fast.
• the available dependent images have not necessarily been retrieved
• upon a transition from a 2D rendering mode to a 3D rendering mode it is determined whether specified image data for a dependent image has already been retrieved. If the image data for the dependent image has not yet been retrieved, it is subsequently retrieved in order to enable rendering of the graphical object in a 3D rendering mode. In this way it is ensured that in addition to the base images all necessary dependent images are available for rendering.
• a method for initializing a rendering module which is switchable between a 3D rendering mode and a 2D rendering mode, and whose output is fed to a graphics subsystem, comprises the steps of:
• an application adapted to perform the necessary steps is advantageously stored on a storage medium.
• the application also includes the rendering module, which is switchable between the 3D rendering mode and the 2D rendering mode.
• an 2D rendering module is available in addition to the switchable rendering module.
• the 2D rendering module is initialized.
• the switchable rendering module is initialized irrespective of the actual current rendering mode in case the graphics subsystem is capable of rendering in stereoscopic mode. In this way it is ensured that in case of switching from the 2D mode to a 3D mode 3D rendering can start immediately without the need to first terminate the 2D rendering module and initialize the switchable rendering module.
• Fig. 3 shows a process of image loading during regular
• Fig. 4 depicts an exemplary process of image loading upon switching of the rendering mode.
• a stereoscopic' scene graph In order to define graphical objects that can be efficiently rendered in stereo 3D mode and in 2D mode, a stereoscopic' scene graph is defined.
• the proposed scene graph specifies and uses stereo pairs of images. Similar stereo pairs form the basis of stereoscopic 3D.
• One image is intended for the left eye and another image is intended for the right eye.
• One image of a stereo pair represents a 'base image' (BI) .
• the other image represents a 'dependent image' (DI) .
• the base image is mandatory, whereas the dependent image is optional.
• Example 1 Example 1
• FIG. 1 illustrates a first exemplary definition of a stereo pair, which uses XML as a declarative language.
• the ⁇ img> element defines an image element. Each such image element carries a unique identifier, specified in the 'id' attribute of the ⁇ img> element.
• the ⁇ file> element defines the source of the image data. Among others, this can simply identify a file on some local file system.
• the above example defines two images named 'ibgd' and 'ibgd_r'.
• 'ibgd' carries a ' stereo_idref ' attribute. This attribute links the two images to form a stereo pair.
• Such a stereo pair can be conveniently used as follows:
• Example 2 illustrates a second exemplary definition of a stereo pair, which also uses XML as a declarative language.
• Example 2
• the ⁇ img> element defines an image element. It carries a unique identifier, specified in the "id" attribute.
• the 'scr' attribute defines the source image data for one image of the stereo pair.
• the 'src_r' attribute defines the source image data for the other image of the stereo pair.
• Example 3 illustrates a third exemplary definition of a stereo pair. This example uses HTML as a declarative language.
• the 'src' attribute of an ⁇ img> element defines the data source for the image.
• a new attribute 'src_r' defines the data source of the associated second image to form a stereo pair.
• decision step 1 it is detected whether 2D output or stereo 3D output is to be generated.
• the mandatory base image BI is used for compositing 2 the graphical object.
• a second decision step 3 detects whether the image to be rendered is a stereo image, i.e. whether in addition to the mandatory base image BI, a dependent image DI is declared.
• the base image BI is used for compositing 4 the left channel output as well as the right channel output.
• the base image BI is used for compositing 5 the left channel output and the dependent image DI is used for compositing the right channel output.
• IM 'image mosaics'
• Such image mosaics IM combine a number of elementary images into a larger image. This is exemplarily illustrated in Fig. 2. This technique decreases the time required to decode all the images at runtime, because each image decoding process includes some runtime overhead to set up the image decoder. Combining elementary images into an image mosaic IM avoids frequent set ups of the image decoder and the associated extra time.
• one particular image mosaic IM does not combine one or more base images BI with one or more dependent images DI .
• the set of base images BI is preferably combined into one or more image mosaics IM, so called base image mosaics (BI-IM)
• the set of dependent images DI is combined separately into one or more different image mosaics IM, so called dependent image mosaics (DI-IM) .
• the separation of images into base images BI and dependent images DI, or into base image mosaics BI-IM and dependent image mosaics DI-IM, allows to implement beneficial rules for an application capable of rendering the scene graph in either stereo 3D mode or 2D mode.
• the application detects at runtime that rendering in 3D mode is not possible in the execution environment, e.g. the application is running on a 2D Blu-ray player or the application is running on a 3D Blu-ray player but only a non-3D screen is connected to the player, when images are to be loaded, any dependent image DI or
• the application detects that stereo 3D mode is possible, the following two modes of loading image resources are preferably supported.
• base images BI or base image mosaics BI-IM as well as dependent images DI or dependent image mosaics DI-IM are loaded into memory as
• this mode includes the case where 3D mode would be possible in the execution environment, but the application is currently configured or signaled to render in 2D mode.
• This mode has the advantage that no dependent images DI or dependent image mosaics DI-IM need to be loaded when transitioning from 2D rendering mode to 3D rendering mode, so a transition is comparably fast.
• This mode could be circumscribed as an 'eager loading' mode.
• the application detects whether the current rendering mode is 3D or 2D.
• 3D rendering mode base images BI or base image mosaics BI-IM as well as dependent images DI or dependent image mosaics DI-IM are loaded into memory.
• 2D mode only base images BI or base image mosaics BI-IM are loaded.
• this mode when transitioning from 2D rendering mode to 3D rendering mode, necessary dependent images DI or dependent image mosaics DI-IM are loaded as needed. This mode could be circumscribed as a 'lazy loading' mode.
• FIG. 3 An exemplary process of image loading during regular operation, i.e. not caused by any mode change, is depicted in Fig. 3.
• a 3D rendering mode is possible. If this is not the case, only a base image BI or a base image mosaic BI-IM is loaded 9 and any dependent image DI or dependent image mosaic DI-IM is ignored. If, however, a 3D rendering mode is possible, the further process depends on the loading mode. Therefore, in a further decision step 10 the loading mode is determined. Of course, the further decision step 10 can be omitted when the loading mode is fixed for a specific implementation.
• a base image BI or a base image mosaic BI-IM as well as a dependent image DI or dependent image mosaic DI-IM is loaded 11.
• a mode change request 13 it is determined 14 whether currently a 3D rendering mode is possible. If this is not the case, no further steps need to be performed. If, however, a 3D rendering mode is possible, the further process depends on the transition type. Therefore, in a further decision step 15 the transition type is determined. In case of a transition from 3D rendering mode to 2D rendering mode, no further steps need to be performed as all necessary base images BI or base image mosaics BI-IM have already been loaded before for 3D rendering. In case of a transition from 2D rendering mode to 3D rendering mode, the further process depends on the loading mode that has been used before for in response to the image load request 7 of Fig. 3. Consequently, in yet a further decision step 16 the previously used loading mode is determined. Of course, the further
• decision step 16 can be omitted when the loading mode is fixed for a specific implementation. In case an eager loading mode has been used, no further steps need to be performed as all necessary dependent images DI or dependent image mosaics DI-IM have already been loaded before. In case a lazy loading mode has been used, the necessary dependent images DI or dependent image mosaics DI-IM are loaded 17.
• the part of an application which is capable of rendering a scene graph is a graphics rendering module.
• Such an application is typically provided on a storage medium together with the content to be reproduced.
• a typical task of the graphics rendering module is 'double-buffering', i.e. a technique where an application draws the next composition into an invisible back buffer, while the current composition is stored in a front buffer connected to the display. When requested, the graphics rendering module copies the content of the back buffer into the front buffer.
• the double buffering technique avoids that intermediate compositions get visible on the display, which potentially causes flicker.
• such a graphics rendering module needs two pipelines, each connected to one back buffer.
• One back buffer is needed for compositing the left channel output, whereas another back buffer is needed for compositing the right channel output .
• stereo graphics rendering module can be designed to support stereoscopic 3D rendering as well as 2D rendering. In the latter case, one of the two pipelines is used to generate the 2D output while the other pipeline remains unused. Further, the stereo 3D graphics rendering module can be designed to support dynamic mode switches between stereo 3D rendering and monoscopic 2D rendering. This means that a stereo 3D graphics renderer as outlined above is very flexible.
• a stereo 3D rendering module allocates two back buffers, each allocating a considerable amount of the image memory.
• a back buffer In case of a Blu-ray player, such a back buffer
• image memory is usually limited, preferably the following beneficial rules for an application capable of rendering the stereoscopic scene graph in either stereo 3D mode or 2D mode are
• the application When the application detects at runtime that rendering in 3D mode is not possible in the execution environment, e.g. because the application is running on a 2D Blu-ray player or the application is running on a 3D Blu-ray player but only a non-3D screen is connected to the player, the application creates and activates a graphics renderer implementation which is capable of rendering in 2D mode only.
• a graphics renderer implementation which is capable of rendering in 2D mode only.
• Such an implementation embeds a single pipeline only, and hence allocates memory to hold only a single back buffer.
• the application When the application detects that stereo 3D mode is possible in the execution environment, the application creates and activates a graphics renderer implementation which is capable of rendering in 3D mode and in 2D mode.
• a graphics renderer implementation which is capable of rendering in 3D mode and in 2D mode.
• 'x' determines the position in horizontal direction
• 'y' determines the position in vertical direction
• 'z' usually only specifies in-front- of/behind relationships between individual elements, i.e. the composition order.
• 'z' is used to determine the composition order of individual elements in the scene graph.

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• Engineering & Computer Science (AREA)
• Physics & Mathematics (AREA)
• General Physics & Mathematics (AREA)
• Computer Graphics (AREA)
• Theoretical Computer Science (AREA)
• Geometry (AREA)
• Software Systems (AREA)
• Multimedia (AREA)
• Signal Processing (AREA)
• Processing Or Creating Images (AREA)
• Testing, Inspecting, Measuring Of Stereoscopic Televisions And Televisions (AREA)
• Image Generation (AREA)
• Signal Processing For Digital Recording And Reproducing (AREA)
• Indexing, Searching, Synchronizing, And The Amount Of Synchronization Travel Of Record Carriers (AREA)

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• 2011
  • 2011-03-31 EP EP11305373A patent/EP2506263A1/de not_active Withdrawn
• 2012
  • 2012-03-19 US US14/004,704 patent/US10332299B2/en active Active
  • 2012-03-19 CN CN201280015813.7A patent/CN103460292B/zh active Active
  • 2012-03-19 JP JP2014501528A patent/JP6113142B2/ja not_active Expired - Fee Related
  • 2012-03-19 WO PCT/EP2012/054761 patent/WO2012130650A2/en active Application Filing
  • 2012-03-19 KR KR1020137025645A patent/KR20140010120A/ko not_active Application Discontinuation
  • 2012-03-19 EP EP12709112.2A patent/EP2691956A2/de not_active Ceased

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